Technical Abstract:
Pichia anomala WRL-076 was discovered by a visual screening bioassay for its antagonism against A. flavus. The yeast could effectively inhibit aflatoxin production and growth of A. flavus. An important requirement for the use of biocontrol agents is the production of large quantities of the microorganisms and the development of formulations to maintain the viability. Four media compositions, I, II, III and IV were used to grow P. anomala WRL-076 to high cell density. Eight different liquid formulations, A, B, C, D, E, F, G and H with or without trehalose additive were developed for cold storage of yeast cells. Viable cell numbers were monitored monthly over by enumeration of colony forming units (CFUs) and by flow cytometry. The data indicate that a large number of the cells are viable after cold storage for more than one year in formulation C, D, E, F, G and H. Trehalose has a remarkable capacity to protect cells and their component macromolecules against an array of environmental stresses. Addition of trehalose to cells grown in media I and II (i. e., formulation E and F) protected the cells resulting in high percentage of viable cells. The long shelf-life of P. anomala WRL-076 and simple formulations will facilitate commercial product development of this superior yeast strain.